Modern farming techniques and philosophy discourage the ploughing of fields into "black land". A field which has been completely plowed, or even strip plowed, is, among other things, susceptible to wind and water erosion, with attendant loss of valuable topsoil. Current modern farming practice calls for grain growers to seed and fertilize a field without plowing the field. This is done by using a zero-till drill which, by means of Coulter disks, seed and fertilizer drills, and packer wheels, sows the seed and the fertilizer directly under the stubble and soil without breaking the stubble and soil to any significant extent.
In situations where the topsoil has been tilled, Coulter disks are not necessary because the seed and fertilizer can be sown by the drills directly into the tilled soil.
In both zero-till drill and seed sowing into tilled soil procedures, the fertilizer is usually injected into the soil at a level 2 to 3 inches below the level at which the seed is deposited in the soil. This encourages the roots of the germinating seed to extend downwardly, rather than laterally or upwardly. Thus, the germinated seed sets down solid roots which in turn encourages strong growth of the cereal plant above the topsoil.
A typical zero-till seeder and fertilizer drill is manufactured by Haybuster Incorporated, North Dakota, U.S.A. The Haybuster drill comprises a rigid frame which is mounted on pairs of tires fore and aft. The Haybuster drill is pulled by a tractor or other suitable vehicle. The rigid frame carries seed and fertilizer hoppers above the frame and underneath, a sub-frame which can be raised or lowered by rotation about laterally extending rocker arms. The sub-frame carries below it a combination of Coulter disks (optional), seed drills and packer wheels, extending in lateral rows across the sub-frame.
A principal shortcoming of the Haybuster drill is that it has a long wheel base which is primarily caused by the construction of the sub-frame and the need to have "swing room" as the sub-frame carrying laterally extending parallel rows of Coulter disks, if present, seed and fertilizer drills and packer wheels is raised and lowered. This is a major disadvantage when the Haybuster drill is drawn over uneven terrain. For example, when the Haybuster drill is drawn over small hills, the seed drills are forced deeper in the soil than should be the case. This means that the seed and fertilizer are deposited in the soil at deeper than optimum depths, which thereby hinders good crop production. The reverse is the case when a dip or hollow in the terrain occurs. The seed and fertilizer are then deposited by the drills at shallow depths in the soil, which is detrimental to good crop yield. To obtain uniform fertilizer and seed deposit depths in the soil, and thereby maximize crop yield, a short wheel base is very desirable because then the zero-till drill can more closely track the contours of the uneven terrain and consistently deposit seed and fertilizer in the soil at optimum depth.
The Haybuster drill has another disadvantage in that when it carries Coulter disks, they are carried in a lateral aligned row. This can create a problem in the field because the uniform in-line "front" presented by the lateral row of Coulter disks tends to collect and build up straw and stubble which must then be periodically cleared away from the Coulter disks. The collected straw and stubble can also interfere with the efficient operation of the Coulter disks.
Another shortcoming of the Haybuster drill is that it is not possible to lift the packer wheels off the soil when the end of a pass on the field is reached. Packed soil is detrimental to crop production on a cropped field and hence it would be advantageous if overpacking could be avoided as much as possible.
A further disadvantage of the Haybuster drill is that the seed and fertilizer drills are set a good distance behind the Coulter wheels. Thus Coulter disks cut the stubble several feet ahead of the following seed drills. This does not present a problem so long as the Haybuster drill is drawn in a staight line and the seed drills are able to follow in the grooves cut by the Coulter disks. However, when the Haybuster drill is towed by a tractor along a curved or uneven path, the seed drills do not necessarily follow in the grooves cut by the Coulter disks. Moreover, on a curved path, the packer wheels which follow behind the seed drills do not necessarily pack the rows in which the seed and fertilizer have been deposited by the seed drills. This non-alignment deficiency tends to defeat the purpose and advantage of the Coulter disk, seed drill and packer wheel combination.
Regarding other prior art, the applicant is aware of U.S. Pat. No. 4,417,530, Ivayl D. Kopecky, granted Nov. 29, 1983 to Haybuster Manufacturing Inc., Jamestown, North Dakota. This U.S. patent discloses and claims a device for planting seed and applying fertilizer including a frame adapted to be moved over the ground and a furrow opener shank carried on the frame.